The present invention relates generally to telecommunications equipment and, more particularly, to an MDI crossover control for providing proper connections between telecommunication transmission lines.
When two cable pairs are used for differential transmission of data between two devices, one pair is used for signal transmit and one pair is used for signal receive. This requires the pairs be reversed on one end to insure that the transmit signal path is connected to the receive signal path and vice versa. This is referred to as Medium Dependent Interface (MDI) crossover.
The original method used for MDI crossover was to use jumper wire on a cross connect termination block. The jumper wire was used to connect one pair to the other to achieve a crossover. When modular patching replaced cross-connect blocks, a special patch cable that reversed the signal pairs on one end had to be used to achieve a crossover function. The special patch cables created a logistical problem because special cordage was required.
A later method used a manual 4-pole double throw (4PDT) located in the network equipment. When actuated, it reverses the electrical connection between the cable pairs to achieve the MDI crossover. This is still a very common technique but does require that a knowledgeable operator configure the network equipment.
Network equipment manufacturers now xe2x80x9chard-wirexe2x80x9d the MDI crossover into the equipment port so no special cables and switch mechanisms are required. This is also a common technique employed in network equipment that has a specific application such as an unmanaged hub. Another method of hardwiring is to use two separate connectors on the same port. One connector is wired with the normal MDI connection and the second connector is wired with the MDI pairs reversed. This method increases the physical size of the product and requires a knowledgeable operator to configure the network equipment.
Application Specific Integrated Circuits (ASIC) used for differential signal transmission may use a solid state switching matrix that is part of the IC. This matrix performs the same function as the manual switch previously mentioned. Unlike the switch, the matrix is actuated or switched automatically by an internal clock signal. This switching continues regardless if a connection has been made to another piece of network equipment. When the ASIC detects a link or integrity pulse from the other piece of network equipment, the switching is halted indicating link integrity pulses have been detected by the receiver, hence proper MDI signal orientation. ASIC solutions are generally proprietary and not commercially available for use with other types of integrated circuits.
According to a first aspect of the invention, there is provided a method of performing automatic crossover in a converter. The method includes the steps of:
(a) detecting when a cable has been plugged into the converter indicating that a signal connection has been made between a device and the converter;
(b) determining if the cable pair""s orientation is correct with a signal input and output of the converter; and
(c) if it is determined in step (b) that the orientation is not correct, effecting a crossover of the cable pairs.
According to a second aspect of the invention, there is provided a system for performing an automatic crossover in a converter. The system includes means for detecting when a cable has been plugged into the converter indicating that a signal connection has been made between a device and the converter, means for determining if the cable""s orientation is correct with a signal input and output of the converter and means for effecting a crossover of the cable if it is determined that the cable""s orientation is not correct.
According to a third aspect of the invention, there is provided an apparatus for performing automatic crossover in a converter. The apparatus includes a detector circuit that detects when a cable has been plugged into the converter indicating that a signal connection has been made between a device and the converter, a cable orientation detection circuit that determines if the cable""s orientation is correct with a signal input and output of the converter, and a circuit for generating a steering pulse if it is determined that the orientation is not correct, wherein the steering pulse effects a crossover.
According to a fourth aspect of the invention, there is provided a crossover control circuit assembly. The assembly includes a medium dependent interface, a relay, a media converter and a detection circuit. The relay is coupled to the medium dependent interface and the media converter circuit is coupled to the relay. The media converter has a signal input and a signal output. The detection circuit is coupled between the media converter circuit and the relay. The detection circuit performs the steps of detecting when a cable has been plugged into the medium dependent interface, determining if the orientation of the cable is correct with respect to the signal input and output of the media converter, and if it is determined that the orientation of the cable is not correct, causing the relay to effect a crossover.